A pyramid would seem to fit the given description.
Pyramid
A geometric figure with a polygonal base and triangular sides is called a pyramid.
A polygonal pyramid.
pyramid
pyramid
All but one face must be triangular. The base can be any polygon, including a triangle.
A polyhedron with a polygon base and triangular sides that all meet at a common vertex is known as a pyramid. The base can be any polygon, such as a triangle, square, or pentagon, and the triangular sides are called lateral faces. The vertex where all the triangular faces converge is referred to as the apex of the pyramid. Each type of pyramid is named based on the shape of its base, such as a triangular pyramid or a square pyramid.
A three-dimensional figure with a polygon base and triangular faces that meet at a common vertex is called a pyramid. The base can be any polygon, such as a triangle, square, or pentagon, and the apex is the common vertex where all the triangular faces converge. Pyramids are named based on the shape of their base, such as triangular pyramids or square pyramids.
a polygonal prism or a polygond
A pyramid.
A pyramid is formed by a polygonal base and triangular faces that connect the base to a single apex. The number of triangular faces in a pyramid is equal to the number of sides on the base polygon. For example, a pyramid with a square base has four triangular faces, while a pyramid with a triangular base has three triangular faces. Thus, the total number of triangles in a pyramid varies depending on the shape of the base.
A pyramid.